Ask the doctor: Should I stop using SPF to get more vitamin D from sunlight, or do I need to take a supplement?

​Dr Grant replies: Let’s start by explaining why it is so important for the whole family (infants included) to take a vitamin D supplement daily. Doses vary by age, so always check the label on your supplement.

Dietary deficiency of calcium, vitamin D or protein can increase bone loss and can lead to osteoporosis over time. Vitamin D is required for calcium absorption. Low levels of vitamin D can result in high parathyroid hormone levels, which can also increase bone loss.

There are many ways to ensure optimal bone health at any age. Firstly, assess your diet for your consumption of dairy products which are one of the best sources of calcium, especially low-fat fortified milk. Not only do they have calcium but added vitamin D and more. Vitamin D also plays a role in the immune and blood clotting system, as well as other vital organ function such as muscle, heart, brain, lungs and liver.

One of the best sources of dietary calcium is dairy milk, cheese and yoghurt (ideally low fat, with no added sugar or sweeteners). Fortified bread/cereal, egg yolk, raw nuts (unroasted/unsalted) and any oily fish (e.g. salmon, sardines, tuna, mackerel etc) also contain calcium and vitamin D, as do some mushrooms and some dark green vegetables.

Secondly, make sure you are getting regular weight-bearing exercise such as brisk walking, hiking, running or HIIT classes in a gym.

Thirdly, avoid cigarette smoking and excessive alcohol consumption (more than three units per day). Excessive alcohol may cause dietary and liver problems and low levels of hormones, which can adversely affect bone health.

Excessive caffeine consumption (more than 300mg-400mg per day) can also increase bone loss by increasing calcium excretion in urine, resulting in the body taking calcium from the bone (depleting your natural calcium store).

Topical retinols are derivatives of the anti-oxidant retinoic acid (vitamin A) and when used long-term (for more than six months) have proven evidence in reducing the effects of sun damage, improving the appearance of fine wrinkles and even for reducing actinic keratosis (non-melanoma precancerous skin lesions). Topical retinols are also very effective in the treatment of mild to moderate acne.

As with all skin types, daily application of SPF (ideally 30+) is strongly recommended year-round to prevent photo-aging (sun damage) and skin cancer. Regardless of retinol use, everyone should apply SPF daily to the face, neck, ears and back of the hands. Moreover, the use of topical retinols may cause skin photosensitivity to UV light making it even more important to apply daily SPF. Ideally, your daily moisturiser should contain SPF and look for products with added hyaluronic acid and antioxidants such as vitamin C.

It’s true to say that sunshine exposure on your skin (for even just 10 minutes) between the hours of 10am and 2pm can cause the natural synthesis of vitamin D3 in the skin. People with darker skin tones will need more sun exposure to get the same benefits, especially in countries like Ireland where there is a lot of cloud cover, therefore they are at higher risk of vitamin D deficiency.

As you age, your skin does not synthesise as much vitamin D and older people may spend more time indoors, further increasing the risk for deficiency. Instead, it is much easier and safer in terms of skin health to take a daily supplement.

Often, vitamin D supplements are combined with vitamin K2, another vital vitamin similar to vitamin D in terms of its role in the body. Vitamin K2 plays a role in dental health and activates proteins in the body that direct calcium into the bones and helps reduce the risk of osteoporosis.

Dr Jennifer Grant is a GP with Beacon HealthCheck